Koffi Djaman

• PhD in Agricultural Engineering University of Nebraska-Lincoln
• Professor (Associate) at New Mexico State University

South-central Nebraska is one of the most extensively irrigated areas in the U.S., with over 65,000 active irrigation wells, and maize is the major agronomical crop produced. Maize production in this region requires supplementary irrigation for maximum productivity. Effective on-farm implementation of full and limited irrigation practices for poten...

Under semiarid climate of the Southwest United States, accurate estimation of crop water use is important for water management and planning under conservation agriculture. The objectives of this study were to estimate maize water use and water productivity in the Four Corners region of New Mexico. Maize was grown under full irrigation during the 20...

Weather conditions in the southwestern United States are variable and influence crop growing periods with late spring and early fall frosts which significantly impact cropping seasons. With the development of new maize hybrids, grain yield, evapotranspiration, and water use efficiency can be substantially impacted by planting density and planting d...

Effective agricultural water management requires accurate, continuous, and transparent accounting of water use in irrigated agroecosystems, especially in water-limited regions where moratoriums may be imposed. Advances in sensor technologies, networking, and data analytics can aid in fulfilling this task by automatically collecting, analyzing and r...

This study aimed to measure maize (Zea mays) plant nutrient content and nutrient removal in grain, and to evaluate the residual soil nitrogen, phosphorus, and potassium as impacted by planting date and density. Field experiments were conducted to evaluate six plant densities and seven planting dates using a split-split plot design with three replic...

This study examined the flood frequencies and amplitudes of annual maximum precipitation and discharge within the Mono River Basin (MRB) in Togo, West Africa. We scrutinized daily historical data from 1961 to 2020, alongside Shared Socio-economic Pathway SSP5-8.5 scenario derived from the Coupled Model Intercomparison Project phase 6 (CMIP6) data f...

Introduction Long-term fertilization affects bacterial, archaeal and fungal communities composition Soil microorganisms play a major role in maintaining soil health and productivity. Here, we examined the impact of two long-term fertility experiments (LTFE) carried out over a period of 25 years on soil microbial community in intensive rice-based ir...

Potato (Solanum tuberosum L.) is one of the crops worldwide produced under different climatic and cropping systems conditions. With the multitude of cultivars and variable relative maturity, numerous studies have shown that nitrogen management in potatoes is a key to tuber yield and quality. Most potato growers apply high amounts of nitrogen fertil...

The original paper dealt with an interesting topic on evaluating dripper-plants spacing for improving tomato yield and water productivity using drip irrigation system in the Sudanian climate in Burkina Faso with the aim to find out the suitable spacing between dripper and plants that may improve crop water uptake, water productivity, and drip irrig...

Increasing water scarcity for agricultural irrigation demands options to maximize yield with available water. Alfalfa (Medicago sativa) is a valuable crop in arid and semiarid regions and is considered a major user of irrigation water. Consequently, an area of established alfalfa was center-pivot-irrigated over two years according to one of four ir...

Reference evapotranspiration (ET 0) is an essential parameter for hydrological modeling, irrigation planning and for studying the impacts of climate change on water resources. The Penman-Monteith method is recommended for estimating ET 0 under all climatic conditions, but its application is limited in regions where data is difficult to access. The...

Analysis of reference evapotranspiration (ET0) trends is essential for understanding the impacts of climate change on water resources. Thus, despite the continuous rise in temperatures, a decrease in evapotranspiration is noted in some parts of the world. This contrast is called the “evaporation paradox” and is thought to be related to the variatio...

Irrigation and nitrogen management are crucial for sustainable potato (Solanum tuberosum L.) production. A field experiment was conducted during the 2022 and 2023 growing seasons at Farmington, New Mexico, to evaluate the performance of two chip potato varieties (Lamoka and Waneta) under three irrigation regimes (full irrigation (FI), 20% deficit i...

Cotton is a relatively new crop in southern Kansas and its effective irrigation scheduling requires information on crop water requirement and water productivity in a given climatic condition. This study aimed to: (1) assess cotton crop actual evapotranspiration, irrigation water requirement, (2) evaluate lint yield and quality, and (3) determine th...

Alfalfa (Medicago sativa L.) requires a large amount of potassium (K) for maintaining forage yield and stand persistence. Therefore, soil inherently low in K levels must be supplemented with K fertilizers. Although several commercial K fertilizers are available on the market, choosing an appropriate K-supplementing source for a particular soil can...

Intensive irrigation and nutrient management practices in agriculture have given rise to serious issues in aquifer water depletion and groundwater quality. This review discusses the effects of irrigation and nitrogen management practices on potato growth, yield, and quality, and their impacts on water and nitrogen use efficiencies. This review also...

Actual crop evapotranspiration (ETa) is measured or estimated using different methods, and its accuracy is critical for water management under precision agriculture. The objective of this study was to compare maize ETa estimated by the two-step approach using a locally developed crop coefficient curve with satellite-retrieved evapotranspiration by...

The discussers sincerely appreciate the work of the authors investigating the combined effect of Biochar and residual plastic film on soil properties and root biomass of the flue-cured tobacco. While much may be derived from the study in terms of Biochar and residual plastic management in flue-cured tobacco, there are some points the discussers wou...

The discussers sincerely appreciate the work of the authors investigating the soil moisture or ET-based smart irrigation scheduling: a comparison for sweet corn with sap flow measurements. While much information may be derived from the study in terms of sweet corn response to irrigation water, there are some points the discussers would like to comm...

Crop evapotranspiration (ETa) is the main source of water loss in farms and watersheds, and with its effects felt at a regional scale, it calls for irrigation professionals and water resource managers to accurately assess water requirements to meet crop water use. On a multi-crop commercial farm, different factors affect cropland allocation, among...

Highlights Water use efficiency and yield potential of 10 rotation crops were tested under dryland and fully irrigated conditions. Pearl millet in grasses, cowpea and sesbania in legumes had great potential as rotation crops with greater yields and WUEs. Irrigation improved water use efficiency of crops compared to dryland conditions. Abstract. Un...

Potato (Solanum tuberosum) is a very sensitive crop to water stress and timely irrigation water management improves tuber yield and quality. The objectives of this study were to (1) investigate soil water dynamics under potato crops across their root zone and (2) estimate potato crop evapotranspiration (ETa) under sprinkler irrigation on the sandy...

Reference evapotranspiration (ETo) is an important parameter in hydrological, agricultural and environmental studies. Accurate estimation of ETo helps to improve water management and increase water productivity and efficiency. While the Penman-Monteith ETo equation enjoys worldwide adoption as the most accurate ETo equation, the number of requested...

Limited water resources and insufficiently developed infrastructure provide challenges to sustainable production of cotton in Western Kansas. This study aimed to (i) assess the actual seasonal evapotranspiration (ETa) and (ii) determine the grass-reference crop coefficients (Kc) for cotton under different irrigated and rainfed conditions. Four irri...

Reference evapotranspiration (ET0) is an essential parameter for hydrological modeling, irrigation planning and for studying the impacts of climate change on water resources. The Penman-Monteith method is recommended for estimating ET0 under all climatic conditions, but its application is limited in regions where data is difficult to access. The al...

Analysis of reference evapotranspiration (ET0) trends is essential for understanding the impacts of climate change on water resources. Thus, despite the continuous rise in temperatures, a decrease in evapotranspiration is noted in some parts of the world. This contrast is called the "evaporation paradox" and is thought to be related to the variatio...

Potato (Solanum tuberosum L.) is a very sensitive crop to water stress and timely irrigation water management improves tuber yield and quality. The objectives of this study were to (1) investigate soil water dynamics under potato crops across their root zone and (2) estimate potato crop evapotranspiration (ETa) under sprinkler irrigation on the san...

Grasses as well as leguminous and non-leguminous broadleaves are the major categories of commonly grown cover crops worldwide. This review focuses on the contribution of cover crops to soil properties. The review first considers the single and mixed cover crops and shows that grass species are desirable for their decay and ability to provide substa...

This report has been prepared by Agricultural Science Center Farmington (ASCF) staff to document the results of the various research projects from the past year and to record data for future reference. These are not peer-reviewed, multi-year research results, but rather a snapshot of the 2021 ASCF activities. Readers are cautioned against drawing c...

Potato is one of the main crops grown worldwide under different climatic conditions. Potato is conventionally produced under intensive tillage practices under the same or different soil types. Research has shown some contrasting effects of the tillage practices on the soil properties, crop growth, yield, and quality. Under the reducing available fr...

Reference evapotranspiration (ET0) is a major factor for water resource management. Although the FAO Penman-Monteith model is the highly recommended for estimating ET0, its requirement of a complete climatic variables has made the application of this model complicated. The objective of this study was to investigate the potential of four machine lea...

Potato is one of the main crops grown worldwide under different climatic conditions. Potato is conventionally produced under intensive tillage practices under the same or different soil types. Research has shown some contrasting effects of the tillage practices on the soil properties, crop growth, yield, and quality. Under the reducing available fr...

Weather conditions in the high plains of Kansas and a decline in water resources affect cotton production. This study aimed to assess the effect of different irrigation technologies, rainfed conditions, and plant densities on soil water dynamics and cotton growth. Results indicated that the Mobile Drip Irrigation 2 (MDI2) had the highest growth cha...

A decrease in water resources, as well as changing environmental conditions, calls for efficient irrigation-water management in cotton-production systems. Cotton (Gossypium sp.) is an important cash crop in many countries, and it is used more than any other fiber in the world.

A decrease in water resources, as well as changing environmental conditions, calls for efficient irrigation-water management in cotton-production systems. Cotton (Gossypium sp.) is an important cash crop in many countries, and it is used more than any other fiber in the world. With water shortages occurring more frequently nowadays, researchers hav...

- Guided and self-guided tours start at 9:00 am - Welcome at 11:00 am front lawn - Follow the tour on Instagram. Each stop is numbered and some videos will give additional info about the field day stops.

The sub-tropical region of West Africa is not only vulnerable to the negative effects of climate change but also to the changes in land management. The goal of this study was to model streamflow in the Mono River Basin (MRB) for the period before (1964-1986) and after (1988- 2011) dam construction. The Soil and Water Assessment Tool (SWAT) using in...

Interest in organic foods is increasing at a moment when humanity is facing a range of health challenges including the concern that some conventionally produced foods may pose possible adverse effects on human and livestock health. Consumers are showing increasing interest in organically grown potatoes due to their nutritional quality and health pr...

Interest in organic foods is increasing at a moment when humanity is facing a range of health challenges including the concern that some conventionally produced foods may pose possible adverse effects on human and livestock health. With the increasing human population, intensive production is increasingly trending towards high-input systems that ai...

Interest in organic foods is increasing at a moment when humanity is facing a range of health challenges including the concern that some conventionally produced foods may pose possible adverse effects on human and livestock health. With the increasing human population, intensive production is increasingly trending towards high-input systems that ai...

Alfalfa (Medicago sativa L.) is one of the most important forage crops to farmers and ranchers in the US. Plants potential yield quality and its persistence are some of the key traits breeders have targeted to improve crop productivity and adaptation. The objective of this study was to evaluate different sets of alfalfa cultivars under fall and spr...

The goal of this study was to model streamflow in the Mono River Basin (MRB) for the period before (1964-1986) and after (1988-2011) dam construction. The Soil and Water Assessment Tool (SWAT) using input data such as a digital elevation model, soil and land use, and daily climate data model was set up, calibrated and validated for the period befor...

Fruit and nut trees production is an important activity across the southwest United States and this production is greatly impacted by the local climate. Temperature is the main environmental factor influencing the growth and the productivity of the fruit and nut trees as it affects the trees’ physiology and the vulnerability of flower bud, flowers,...

Performance tests for grain corn, grain sorghum, forage corn, forage sorghum and sorghum sudangrass were conducted at the Agricultural Science Centers at Artesia,Clovis, Farmington, and Tucumcari New Mexico in 2020. This report contains information from all Agricultural Science Center corn and sorghum tests; however,it is possible that not all loca...

Limited water resources coupled with the increase of the human population calls for more efficient use of water in irrigated agriculture. Potato (Solanum tuberosum L.) is one of the most widely grown crops worldwide and is very sensitive to water stress due to its shallow rooting system. With the dilemma of potato sensitivity to drought and limited...

Highlights Four summer cover crops under two irrigation regimes were tested for soil wind erosion control. Soil aggregate stability and wind erosion losses were improved with plant cover in the peak summer. Sorghum sudan is a prominent summer species for wind erosion control in the arid southwest. Abstract . Cover crops can have significant impact...

Consistent production of high alfalfa yields is the result of selecting good varieties and implementing good management techniques. Soil fertility should be maintained at recommended levels based on soil tests, irrigation should be properly applied, weeds and insects should be con-trolled using appropriate cultural and/or chemical methods, and harv...

The objective of this study is to perform trend analysis in the historic data sets of annual and crop season [May–September] precipitation and daily maximum and minimum temperatures across the southwest United States. Eighteen ground-based weather stations were considered across the southwest United States for a total period from 1902 to 2017. The...

Climate change has seriously impacted water availability and agriculture production in arid and semi-arid climates. Estimation of actual crop evapotranspiration (ETa) is critical for agricultural water resource management and proper irrigation scheduling. This study aimed to (1) estimate the reference evapotranspiration (ETo) and four vegetables ac...

This study has investigated and compared the contribution of water balance components over the period before Nangbeto dam installation (1964-1986) and the period after the same dam installation (1988-2010). The datas were mainly water balance component outputs generated from calibrated Soil and Water Assessment Tool over the two periods in the Mo...

The highly variable weather under changing climate conditions affects the establishment and the cutoff of crop growing season and exposes crops to failure if producers choose non-adapted relative maturity that matches the characteristics of the crop growing season. This study aimed to determine the relationship between maize hybrid relative maturit...

Understanding evapotranspiration and its long-term trends is essential for water cycle studies, modeling and for water uses. Spatial and temporal analysis of evapotranspiration is therefore important for the management of water resources, particularly in the context of climate change. The objective of this study is to analyze the trend of reference...

Alfalfa is one of the most nutritive and high-yielding forage legumes planted in rotation with cereal crops across the United States. Under semiarid and arid climates with limited water resources, sustainable management of the available resources is required. The objective of this study was to investigate the effect of different irrigation regimes...

The discussers would like to thank the authors of the original paper that evaluated some temperature based methods estimating reference evapotranspiration in the Yucatán Peninsula, Mexico. This work is of great importance for the study area for better water management under rainfed and irrigated agriculture as water resource for agriculture is dimi...

Solar radiation is one of the most important climatic parameters that is involved in different environmental, hydrological, agricultural applications while not always measured at all weather stations due to the high equipment and maintenance cost. The objectives of this study were to evaluate the performance and accuracy of twenty temperature based...

Reference evapotranspiration (ET0) is a key element of the water cycle in tropical areas for the planning and management of water resources, hydrological modeling, and irrigation management. The objective of this research is to assess twenty methods in computing ET0 in the Senegal River Basin and to calibrate and validate the best methods that inte...

The mission of the New Mexico State University Agricultural Science Center at Farmington is to conduct research, demonstration, and educational programs that will best fill the needs of the Agricultural community of San Juan County and the Navajo Nation in particular, and the State of New Mexico, Four Corners Region, and Nation in general. Projects...

Alfalfa is one of the most important, nutritive, and high yielding forage legumes planted across the US. Fall dormancy in alfalfa influences forage yield characteristics and the plants persistence mostly under the cold and temperate climate. The objective of this study was to evaluate alfalfa cultivars with different fall dormancy-ratings for their...

Potato psyllid (Bactericera cockerelli) is one of the most important pests in potatoes (Solanum tuberosum L.) due to its feeding behavior and the transmission of a bacterium (Candidatus Liberibacter solanacearum) that causes zebra chip disease, altering the quality of the potato tuber and the fried potato chip or french fry. This pest is thus a thr...

The study was conducted to monitor the population dynamics of six major insect pests at the NMSU Agricultural Science Center at Farmington (ASC-Farmington) and within an adjacent commercial farm (Navajo Agricultural Products Industry, NAPI) for more effective and efficient pest management during the 2013-2019 period. Specific pheromone traps, stick...

Soil moisture content early growing season is determinant for crop season planning mainly a decision on planting date. In the region where off season or early season precipitation does not much the conditions for seed germination and plant growth/development, preplant irrigation is applied to meet these conditions. Also, under limited water availab...

The potato chip industry has critical requirements regarding tuber physical and chemical aspects and these requirements are the characteristics targeted by chip potato breeding programs. This study aimed to evaluate 33 chip potato cultivars for the tuber yield and some physical and chemical characteristics of the tuber and potato chips at harvest a...

Reference evapotranspiration (ETo) is an important parameter in hydrological, agricultural and environmental studies. Accurate estimation of ETo helps to improve water management and increase water productivity and efficiency. While the Penman-Monteith ETo equation enjoys worldwide adoption as the most accurate ETo equation, the number of requested...

Soil salinity is a threat to crop production in the Senegal River Delta where salt intrusion increases soil electrical conductivity and most of farmers had abandoned their rice farms. The objective of this study was to evaluate an integrated management to improve rice productivity under saline soil condition in the Senegal River Delta. Field experi...

L’estimation de l’évapotranspiration (ET), une des composantes principales du cycle hydrologique et bon indicateur du changement climatique, est importante pour tous les programmes de gestion de l’eau. Huit méthodes d'estimation de l'évapotranspiration sont ainsi évaluées et l’impact de la variation des paramètres climatiques sur l’évapotranspirati...

Estimation of yield reduction in crop caused by the salinity stress is mostly based on variations of soil electrical conductivity and the severity of water stress. Crop response curves to salinity were developed without considering ion toxicity and nutritional imbalance in the plant. The objective of this study was to explore the possibility of usi...

Lowland irrigated rice is the predominant crop produced in the Senegal River Valley characterized by very low annual rainfall, high temperatures, and low relative humidity. The Senegal River is shared by Senegal, Mali, Mauritania, and Guinea, and serves as the main source of irrigation water for the adopted double rice cropping system. Developing a...

Recognition and understanding of impacts of any crop and (or) soil management practice on crop water use is equally crucial as its intended impacts. One such practice that has gained adoption among producers in the U.S. maize growing regions is conservation tillage, aiming at maintaining about 30-40%, or more, of residual vegetative cover on the so...

Growing rice in saline soils by minimizing damage on growth and yield remains a challenge. We conducted field experiments in the Africa Rice research field located in the Senegal River delta (16° 11’ N, 16° 15’ W) to study the effects of three management options of fertilization e.g. (i) nitrogen, phosphorus, and potassium fertilization: NPK; (ii)...